The present exemplary embodiments relate to automotive, rail, ship traffic and illumination signals. They find particular application in conjunction with utilizing light emitting diodes with automotive, rail, ship traffic and illumination signals. One particular application for such an LED automotive, rail, ship traffic and illumination signal is to substitute a three lamp signal into a single integrated signal under one housing. However, it is to be appreciated that the present exemplary embodiment is also amenable to other like applications.
Automotive, rail, ship traffic and illumination signals are employed to regulate motorists and pedestrians via various commands. These commands are provided by various illuminated elements with particular colors and/or shapes that are each associated with an instruction. Elements are conventionally illuminated via incandescent bulbs which use heat caused by an electrical current to emit light. When electrical current passes through a filament (e.g., tungsten), it causes the filament to heat to the point that it glows and gives off light. Such illumination can be covered with a colored lens and/or template to provide a meaningful instruction that can be viewed in a variety of external lighting conditions.
The filament is a resistive element in the incandescent bulb circuit. The amount of current drawn by the filament is proportional to its impedance. This impedance value increases as the temperature of the filament increases. Thus, a conventional lamp has a larger initial current draw which drops in proportion to the increase in the filament impedance. This variation in current draw is known and a predetermined range can be utilized to monitor the lamp operation. As such, a lamp failure condition can be identified based on the amount of current drawn by the filament. In one example, the filament fails (e.g., breaks) causing the impedance to approach an infinite value and the current value to decrease to almost zero. If the current drawn is outside of the predetermined range, a responsive action can be initiated by a current monitor or other control system.
Unlike the incandescent-based lamps, LED-based lamps consist of an array of LED elements, which draw much less power. LED-based lamps have numerous advantages over incandescent lamps, such as greater energy efficiency and a longer lifetime between replacements than conventional signals. Some of the longer lifetime results since a plurality of LEDs are employed, wherein a light can be utilized even if some of the LEDs in the array have failed.
However, there are some drawbacks related to LED signal designs. Current designs require three lamps to fulfill signaling needs utilized with conventional incandescent lamp housings. In addition, current multiple color LED signals are susceptible to color mixing failure due to poor insulation design.
What are needed are systems and methods to provide multi-color signal designs with a single integrated signal to provide uniform light output.